Circuit Training: Basic Electronics at the Library

This week’s Sizzling Science theme for fifth and sixth graders at the Burlingame Library was Fun with Electronics.  For this one, I stole an idea from the Maker Faire in San Mateo, as well as a project recommended by my coworker, Carbelle Imperial.  The first was a popsicle stick flashlight, and the second a Brush Bot.  This was by far the most expensive workshop I’ve done so far, since I bought the Brush Bot kits from the Maker Shed (a pack of 12 costs $34.99, and I needed 2 packs).

I started out by talking to the kids about electronics, asking them where the word comes from, and discussing what electrons are (one of the three parts of an atom, and the one that carries a negative charge).  I brought out a AA battery, and pointed out the positive and negative terminals.  I explained that a chemical reaction inside the battery causes electrons to build up at the negative end.  The electrons want to travel to the positive end, but cannot travel through the battery itself because of a substance inside called a separator.  (I passed around this diagram from Online Digital Education Connection to illustrate the different parts of the battery.)  I pulled out a piece of aluminum foil and used it to connect the two battery terminals, then walked around to let the kids feel how hot the foil had become, using it as an illustration of a very basic circuit.

It was clear that three or four of the kids already had a great deal of background knowledge of electronics, and were quick to answer questions.  Most of the group stayed quiet though, so it was hard to gauge how much they knew.

I told the kids that they would be using a simple circuit to make a flashlight, and asked them what parts they thought they would need (some of them had already sneaked a peek at my model when they came in the door, so they knew a lot of the answers).  The parts were: a 5mm white LED, a 3-volt lithium coin battery, 1/2″ copper foil tape (which I had pre-cut), jumbo-sized popsicle sticks, small binder clips, and Scotch tape.  We talked a little bit about the function of each part, and I pointed out that the LED had a long leg (the positive lead), and a short one (the negative lead).

In retrospect, I should have handed out each part a step at a time.  As it was, I handed out all the materials at once, and a number of the kids jumped right in without waiting for instructions.  That left me with a lot of troubleshooting to do, and several of them had to start over.  On the other hand, making mistakes and then correcting them may have taught them more than blindly following the steps, so I guess it worked out.

Anyway, the basic process is this:

1) Run a strip of copper foil down one side of the popsicle stick.  Make a small roll of foil at the end, leaving sticky spot close to the center of the stick.

2) Attach the battery to the sticky roll of foil.  The positive (+) side of the battery should be down, touching the foil.  (This was one of the most common mistakes).

3) Clip the binder clip on the end of the popsicle stick closest to the battery.  Flip the metal leg of the clip down.  It should rest on top of the battery.  If it doesn’t reach, adjust the foil and battery to move the battery closer.

4) Flip the popsicle stick over, and run the second strip of copper foil down that side.  Again, when you flip the metal leg of the binder clip down, it should rest on the foil.

5) Place the LED on the end of the popsicle stick opposite the binder clip, with the long leg (positive lead) straddling the side with the battery.  Both legs should be touching the foil tape on each side of the popsicle stick.  If both legs of the binder clip are down, the LED should light up.  If it’s working, tape the legs of the LED down with the Scotch tape.

6) Now you have a simple flashlight with a switch.  To turn it off, flip the top leg of the binder clip back away from the battery.

A completed popsicle stick flashlight

A completed popsicle stick flashlight

The bottom side of the popsicle flashlight

The bottom side of the popsicle flashlight

Some common problems the kids ran into were: putting the LED on backwards (with the short leg on the battery-side of the popsicle stick instead of the long one); running the copper tape over the end of the popsicle stick (in those cases, I just tore the foil, so it was no longer connected); putting the battery on upside down (with the positive side facing up; and putting the battery too close or too far away from the binder clip (sometimes the kids had the hold the binder clip down against the battery to keep the light from flickering). Incidentally, you could make the flashlight with the positive side of the battery facing up, as long as the LED was also attached the opposite way, with the long leg facing the battery-side of the popsicle stick.

I did this project with the kids all sitting in a circle on the floor, to make it easier to distribute supplies and handle questions.  The funny thing was that this project was intended to be a more defined, step-by-step activity, but by now the kids were so used to coming up with their own ideas and prototypes, that many of them went off to tinker with the design, and add extra LEDs (one boy had five!).

A flashlight with 5 LED's

A flashlight with 5 LED’s

Once everyone had a working flashlight, I asked them to move to the tables, and brought out the Brush Bot project.  This one was much more straightforward.  It’s basically a tiny robot made from the head of a toothbrush, a vibrating micro pager motor (the thing that makes cell phones vibrate) with adhesive on one side, and a coin battery.  The coin battery is encased in a plastic cover with two wires coming out.  I had cut the heads off the toothbrushes ahead of time, cut the adhesive tape included with the kit into small pieces, and trimmed the wires, stripping the plastic back to leave a 1/4″ of copper.

All the kids had to do was stick the motor on top of the battery, use a piece of adhesive to stick the battery onto the toothbrush, and twist the ends of each of the wires from the motor around the ends of one of the battery wires (it doesn’t matter which one).  If it works, the motor vibrates, and the brush twirls around (the battery and motor will also move around without the toothbrush, so it might be fun to experiment with that or with other types of bases).  The kit comes with stickers for the kids to decorate their robots.

A brushbot decorated with pipe cleaners

A brushbot decorated with pipe cleaners.  The small black circle on the top is the vibrating motor.  The yellow disc beneath it is the battery.  It is attached to the toothbrush with an adhesive strip.

I had to do a fair amount of troubleshooting with this project too.  The biggest, and most frustrating, problem was that some of the batteries didn’t seem to work. (I checked them over later, and found that they had lost some of their voltage.  They could still light an LED, but were no longer strong enough for the motor.  I did find a simple workaround though: I had a few coin batteries left over from the flashlight project, so I helped the kids use Scotch tape to attach one of the motor wires to the positive terminal of one of those batteries, and the other wire to the negative terminal.  It worked just as well, and helped reinforce the idea of creating a circuit. In fact, I think if I could find a cheap source for the micro pager motors, it might be an easier and less expensive way to do this project.

A Brush Bot with the motor attached directly to the positive and negative terminals of a 3V button battery

A Brush Bot with the motor attached directly to the positive and negative terminals of a 3V coin battery

I gave the kids some pipe cleaners to add appendages to their robots.  By this time, they were off creating all kinds of new designs.  My favorite was a kid who attached a toothbrush head to his popsicle stick flashlight, and made a vibrating toothbrush with an on/off switch!


A vibrating toothbrush with on/off switch

I’m still amazed by the kids in these workshops.  They have so much creativity and enthusiasm, and I’m almost sad to see this workshop series come to an end.  Next week’s theme is Hot and Cold, so we are making ice cream in a bag and homemade thermometers.  I’m just hoping it’s not too messy!  Wish me luck!

Marshmallow Warfare! Fun with Physics at the Library


This week’s theme for the Sizzling Science program for grades 5 and 6 at the Burlingame Public Library was Fun with Physics.  We made marshmallow catapults, and a huge mess, but it was fun!

I started out by asking the kids what they knew about physics.  One of them described physics as the study of motion, which was a good lead-in to our project.  We talked about why understanding how things move is important, for everything from planes and rockets to much simpler tools like spears and rocks.  We talked briefly about the history of catapults, which originated in Ancient Greece and were used widely in the Middle Ages to hit castle walls, or sending flaming projectiles (or disgusting, illness-producing ones like garbage or corpses) onto the castle grounds. (I forgot to mention that catapults are even used today to launch planes from ships.)

I brought out my kids’ Angry Birds: Knock on Wood Game, which includes a simple plastic catapult for launching a toy bird, and demonstrated it, asking the kids how it worked.  We talked about potential energy (the energy stored up when you pull the launcher back), and kinetic energy (the motion energy released when the toy bird flies into the air).  We talked about the different things to consider when targeting with a catapult: the amount of tension you apply when you pull the launching arm back, the vertical speed (how high the projectile flies), the horizontal speed (how far it flies), and gravity (how fast it falls).

I told the kids that they would be designing and creating their own catapults, and had them break into pairs.  I passed out pictures of different catapult designs, including this one from Z Home Team, this one from, and this one from (I had made a sample of this one, except I used a spoon instead of a popsicle stick with a cup on the end.  I gave them a few minutes to discuss what they wanted to make while I set out the supplies.  The materials I provided were: small wooden skewers,wooden clothespins, rubber bands (all sizes), large popsicle sticks, masking tape, plastic spoons, marshmallows (mini, regular, and jumbo).  I told them they could each make their own catapult, but they could work with their partner to brainstorm and refine their design.  Then I set them loose to gather supplies and build.

They spent the rest of the hour building different types of catapults.  Most of them set out copying the designs I provided, but almost all of them ended up making changes, or coming up with something entirely new.  A couple made handheld models (more like a slingshot), and one boy made a masking tape “cup” so he could launch several marshmallows at once.  Some of them worked eagerly with their partner, while others barely even spoke to theirs.  A couple asked for my help trying to copy a design, but I thought it was interesting that as soon as I left them, they both created something original. Here are some of the designs the kids came up with:






Soon there were marshmallows all over the room, and I had to establish a “non-human targets only” rule.  I did put out printouts of a castle, folded into thirds so it could stand up, on each of the tables for the kids to use as a target.  Originally, I had imagined them taking turns shooting at the paper castles, to see which catapults were the most accurate and which could shoot the farthest, but they were all engaged in different parts of the design process for the whole hour.  In the end, I think that was the biggest takeaway: the experience of testing out a design, refining it or rebuilding it entirely, and testing again.  Afterwards, one mom commented that her daughter had taken another class a while ago where they took the kids step-by-step through the process of building the Z Home Team-style catapult, but that she thought it was a lot more fun to let the kids design their own (a big relief to me!).

I had actually prepped a whole other project–a balloon launcher–but we never got to it.  It’s super simple.  You cut the bottom out of a plastic cup (which I had done ahead of time).  Then you tie a knot in the end of an uninflated balloon, and cut the bottom out of it.  You stick the knot through the hole in the bottom of the cup, then stretch the open bottom of the balloon around the cup’s base.  After that, you can put a marshmallow, or some other small object, inside the balloon, stretch the knot back, and let go.  It’s very effective!  I actually demonstrated to a few of the kids who were still hanging around while I was cleaning up, and they were very impressed.  I gave them each a cup and a balloon to take home.


I’m still surprised how much I’m enjoying this classes, even though they are different than anything I’ve done before.  The kids have so much creative energy and ideas, and it’s amazing to see them in action.

Next week’s theme is Electronics.  I’ve ordered Brush Bot kits from the Maker Shed, and am thinking of pairing that with a popsicle stick flashlight.  Both of those projects are much more defined than this week’s catapult challenge, so I’m curious to see how they go.  I’d appreciate any advice anyone has, or other fun, easy electronics projects.

Picnic Time for Teddy Bears: Storytime about Stuffed Animals

Teddy Bear Picnic Day is July 10 (who thinks these things up, and how do I get that job?), so this week I did a Teddy Bear storytime.

Year ago, when I was working at the Woodside Library, we used to do a Teddy Bear Picnic every year.  The kids would bring a favorite stuffed animal, and we would read teddy bear stories, sing songs, and hold a contest where every stuffed animal received an award (softest bear, silliest bunny, and my favorite (for the tattered ones)…most loved).  We even had a teddy bear doctor, who would give each animal a check-up.  This was always hilarious, because the kids would present all kind of symptoms: “My bear has a fever.” “My bunny has a stomach-ache.” “My Spiderman was shot!”  My coworker would examine each animal, and write them a prescription, like “Give three hugs each day.” Then we would serve Teddy Grahams and apple juice, and send them on their way.  It was always a highlight at the end of summer.

So I was feeling a bit nostalgic when planning this storytime, and dug out some of my favorite books.  Here they are:


Where’s My Teddy? by Jez Alborough ( link)

My friend Kerri Hall shared this book with me when we were in library school at UNC, and I’ve loved Jez Alborough ever since.  It’s a rhyming story about a boy named Eddie, who has lost his teddy, Freddie.  While nervously searching through the forest, he finds his teddy bear, only to discover that he’s grown to an enormous size.  But then a giant bear appears, moaning that his teddy bear has suddenly shrunk.  The boy and the bear are equally terrified to see each other, and both grab their own teddy bears and run “all the way back to their snuggly beds, where they huddled and cuddled their own little teds.”  The rhymes are so catchy, I can almost recite this book by heart, and the illustrations are large, and adorable.  The page with the frightened bear and boy always gets a laugh.

my friend bear

My Friend Bear by Jez Alborough ( link)

I was planning to read That Rabbit Belongs to Emily Brown by Cressida Cowell, but the kids seemed to enjoy Where’s My Teddy? so much that I decided to read the sequel (actually it’s the third book in what is actually a picture book trilogy with It’s the Bear, but I’ve read it often as a stand-alone).  In this one, Eddie is walking in the woods with Freddy, and wishing his teddy bear could talk.  Once again, he sees the giant teddy bear, but this time he knows who its owner is.  Sure enough, along comes the bear, and frightened, Eddie hides behind the big teddy.  This leads to a misunderstanding, where the bear thinks his teddy bear can talk, and after sorting all that out, the boy and the bear end up becoming friends.  It’s funny, like the first book, but also sweet, and the ending got a few “Awws” from the parents.

dear bear

Dear Bear by Joanna Harrison ( link)

This is one of my favorite picture books, and one that would work well for a letter-writing theme.  Katie is terrified of the bear she is sure is living in the closet under the stairs.  She tells her mother, who suggests that she write the bear a letter and tell him to go away, which she does.  She is surprised to receive a letter back from the bear, thanking her for the suggestion because he needs a vacation.  When he comes back, he leaves a present for Katie outside the closet door.  The two exchange letters back and forth, until finally the bear invites Katie to a tea party under the stairs.  Nervously, she accepts, but when she arrives, she finds, not a big scary bear, but a large friendly teddy bear.  One of the kids asked how the bear could write letters, and then sagely said, “Maybe her parents wrote the letters.”  The book definitely hints at this, although it never says it outright.


Corduroy by Don Freeman ( link)

One of my all-time favorite books from my own childhood, and one I still love to read.  It’s such a simple story, about a department store teddy bear who loses the button to his overalls, and goes on a quest to find it.  The humor of Corduroy’s interpretation of the world is timeless: the escalator is “a mountain,” the mattress department is “a palace.” Of course, most mattresses nowadays don’t have the “buttons” on the top that Corduroy mistakes for his own missing button.  But it’s still one of the few picture books I know that depicts a family in an apartment instead of the typical suburban house, as well as featuring a beautiful African-American girl who saves the day by adopting Corduroy from the store.  (Incidentally, I stumbled across this blog post by Lisa Rosenberg, the real-life inspiration for Corduroy’s Lisa). There’s been a lot written recently about the lack of diversity in picture books.  I’m acutely aware of that here in the Bay Area, where most of my storytime audiences look nothing like the kids in the books I’m reading.  Corduroy does a wonderful job of creating a lovable, classic story while silently conveying the message that children come in all different shades and backgrounds, and any of them can be a hero.  Plus I always get choked up on the last page.


Going on a Bear Hunt

This was one of my favorite activities when I was a kid, and I love to throw it into a storytime.  The kids echo most of the lines (the ones in parentheses).  I like to play up wiping grass off my pants, and the mud off my feet, and shaking off the water from the lake.  It’s always a hit:

We’re going on a bear hunt!
(We’re going on a bear hunt!)
It’s a beautiful day!
(It’s a beautiful day!)
We’re not scared!
(We’re not scared!)

We’re coming to some grass.
(We’re coming to some grass).
Can’t go over it.
(Can’t go over it.)
Can’t go under it.
(Can’t go under it.)
Have to go through it.
(Have to go through it.)
Swish! Swish! Swish! Swish! (Rubbing hands together)

We’re coming to some mud.
(We’re coming to some mud.)
Can’t go over it.
(Can’t go over it.)
Can’t go under it.
(Can’t go under it.)
Have to go through it.
(Have to go through it).
Squilch! Squelch! Squilch! Squelch! (Clapping hands together).

We’re coming to a lake.
(We’re coming to a lake.)
Can’t go over it.
(Can’t go over it.)
Can’t go under it.
(Can’t go under it.)
Have to swim across it.
(Have to swim across it.)
Splish! Splash! Splish! Splash!

We’re coming to a cave.
(We’re coming to a cave.)
Can’t go over it.
(Can’t go over it.)
Can’t go under it.
(Can’t go under it.)
Have to go inside.
(Have to go inside.)
It’s dark in here…
(It’s dark in here…)
It’s cold in here…
(It’s cold in here…)
Two yellow eyes…it’s a bear!

Swim across the lake!
Run through the mud!
Run through the grass!
Into the house!
Slam the door!
Lock it!
We’re never going on a bear hunt again!

Teddy Bear, Teddy Bear

We have a collection of animal puppets in our kids area at the library, so for this song I had the kids each pick a puppet to act it out with.  Then I asked the kids what else they would like the puppets to do.  One girl said, “The Hokey Pokey!” So we did the Hokey Pokey with the puppets, which was a lot of fun.  The turning around part is a bit hard with puppets, but because they were animals, we could put their noses in, and their ears and tails and tummies.  Here’s the teddy bear song (you can also just chant it):

Teddy Bear, Teddy Bear,

Turn around.

Teddy Bear, Teddy Bear,

Touch the ground.

Teddy Bear, Teddy Bear,

Tie your shoe.

Teddy Bear, Teddy Bear,

I love you!

The Teddy Bear’s Picnic

This is great song by John Walter Bratton, with lyrics by Jimmy Kennedy.  The best ukulele version I’ve found is on Doctor Uke (  It’s kind of a tricky song to sing because of the chord change.   My favorite version by far is the one by Jerry Garcia, which you can listen to here:

CRAFT: PomPom Creatures

PomPom Creature by Kiley

PomPom Creature by Kiley

PomPom Creature by Olivia

PomPom Creature by Olivia

The biggest challenge with this was finding a way to stick the pompoms together.  I gave the kids tacky glue, which worked okay, but I’d love any suggestions on the best way to attach pompoms.  It was still a fun craft, and I loved the way the creatures came out.


I Lost My Bear by Jules Feiffer ( link)

I was hoping to read this book, but unfortunately our branch’s copy was out, and the one I ordered from another library didn’t arrive in time.  It’s a great story about a little girl who is looking for her lost teddy bear.  Her mom tells her to think like a detective, and the hunt begins.  I especially love her sister’s suggestion that sometimes when you throw another stuffed animal, it will find the lost one (I actually tried that in the park once when my son lost a Lego R2D2, and it actually worked!).

Knuffle Bunny by Mo Willems ( link)

I didn’t read this one because I shared it fairly recently, but of course I have to include it in my list of favorite stuffed animal stories.  When Trixie (who is too young to talk) goes with her dad to the laundromat, she loses her beloved Knuffle Bunny.  She tries everything she can to make her Daddy understand that Knuffle Bunny is missing, including going boneless, but he just doesn’t get it.  Luckily, Trixie’s mom knows exactly what’s wrong, and the whole family rushes back to the laundromat.

That Rabbit Belongs to Emily Brown by Cressida Cowell ( link)

I meant to read this one, although I can’t do it nearly as well as my former boss, Thom Ball.  Emily loves her stuffed rabbit, Stanley.  Unfortunately, Queen Gloriana also has her sights set on Stanley, even though Emily refuses to give him up.  Finally, the Queen kidnaps Stanley, but complains that he no longer looks happy.  So Emily teaches her the secrets of having a happy toy companion of her own.

I Must Have Bobo! by Eileen Rosenthal; illustrated by Marc Rosenthal ( link)

I like this one for toddler storytime.  Willy loves his toy monkey, Bobo, but so does Earl the cat.  A simple story with funny illustrations, as Willy has to constantly search for Earl’s latest hiding place.

What are your favorite books about stuffed animals?

Crazy Chemistry: More Summer Science in the Library

Although I was nervous last week about my first summer science workshop for 5th and 6th graders at the Burlingame Public Library, I was surprised at how excited I was to do this one.  I had set the theme as “Crazy Chemistry,” but had trouble finding projects that were not too time-consuming or involved equipment that would difficult to use in the library.  I finally settled on making a naked egg, an acid-base experiment, and a homemade lava lamp.  It ended up being a lot of fun, and thankfully did not end in a giant mess on the carpet.

Here’s what we did:


A Naked Egg

A Naked Egg

I learned about this from my coworker, Carbelle Imperial, who had demonstrated it in her Make It classes at the Pacifica-Sharp Park Library. I added extensions from Steve Spangler Science (Here’s his description:

This was really more of a show-and-tell than a hands-on project, but it made a great lead-in to the topic of chemistry.  I had soaked three eggs in vinegar in my refrigerator three days before.  After the first 24 hours, I put one of the eggs in water that I had dyed green, another in corn syrup, and a third in fresh vinegar.  Basically, the vinegar, (acetic acid) reacts with the calcium carbonate in the eggshell and slowly dissolves it, leaving only a soft translucent membrane to hold the egg white and yolk.  The egg in fresh vinegar also absorbed extra fluid, making it much larger than normal.  The egg in the green water was also supposed to swell to a larger size, but mostly it just turned green (I think I should have left it in the vinegar for at least another day before putting it in the water).  The egg in corn syrup shrank, and became slightly saggy, since some of the water molecules had passed from the egg into the syrup.

Naked Egg Soaked in Corn Syrup

Naked Egg Soaked in Corn Syrup

To start this week’s workshop, I had the kids sit in a circle on the floor.  We talked briefly about chemistry, and how it is the study of matter.  I said that I always think of mad scientists mixing chemicals, but that chemistry can be used to identify and learn more about substances, as well as to make new things.  Then I pulled out a fresh egg and a bottle of vinegar.  I put the egg in a plastic container, which I filled with vinegar.  After a few seconds, tiny bubbles began to form all over the surface of the egg.  I explained that vinegar is a mild acid that dissolves the shell around the egg.  Then I passed around each of my naked eggs, one at a time, and explained each one.


The Naked Egg discussion made a great intro to the next project.  Since we had been working with vinegar, a mild acid, I said we were now going to find out how to determine if something was an acid or a base.  I asked the kids if they knew of an example of a base, giving them the hint that it was something that reacts with vinegar.  One of the kids guessed baking soda, so I pulled some out and gave a very brief demo of baking soda mixed with vinegar in a plastic container.

Before the class, I had put a head of red cabbage in my juicer and diluted the juice with water in a large jar.  I passed this around for the kids to smell (P-U!), and also showed them another head of cabbage so they would know what it looked like.  I explained that red cabbage leaves contain a substance called anthocyanin, which changes color when it is exposed to an acid or a base.  I poured a small amount of my cabbage juice into two Dixie cups, and then put a tiny amount of vinegar in one, and baking soda in the other.  The vinegar turned the cabbage juice bright pink, while the baking soda turned it a blue-green color.

Left: Red Cabbage Water mixed with Baking Soda (a base); Center: Red Cabbage Water alone; Right: Red Cabbage Water mixed with vinegar (an acid)

Left: Red Cabbage Water mixed with baking soda (a base); Center: Red Cabbage Water alone; Right: Red Cabbage Water mixed with vinegar (an acid)

I then pulled four plastic bottles containing different “mystery” substances, labelled A, B, C, and D, and told the kids that they were going to test each one to determine whether it was an acid or a base.  (A was lemonade, B was baking soda mixed with water, C was vinegar, and D was water).  I divided the kids into pairs, and gave each of them four Dixie cups.  I poured a small amount (about an eighth of the cup) of the cabbage juice into each of their cups, and gave them paper and pencils to take notes on their results.  I passed around the different mystery bottles, with a straw to use as a dropper for each one (I showed them how to dip the straw into the liquid, and put a finger over the end to carry a small amount of the liquid over to the testing cups).

The kids seemed to have fun doing the experiment.  Many of them guessed that A was lemonade (the yellow color was a giveaway).  They were confused about the water, which of course didn’t have any effect on the cabbage juice, but a number of them figured that out too.  I was impressed by the notes that they took.  Several of them made simple charts to track the results, while one team made a number of observations about the look and smell of each liquid.

At the end, I asked the kids which of the substances they might want to drink, and asked if anyone would like some Mystery Liquid A.  I had a couple of bottles of lemonade set aside, and we took a short break to drink some.  I explained that lemonade contained citric acid, and joked that they could tell people they had been drinking acid at the library (ha ha).


Lava Lamp with Alka Seltzer added

Lava Lamp with Alka Seltzer added

This project appears on a lot of web sites, including Steve Spangler Science:  It’s very simple, but it was a big hit with the kids.  I started out by showing them one I had pre-made, a water bottle filled with vegetable oil and water that I dyed green with food coloring.  I asked the group why the water and oil were separated.  Most of them knew that oil and water didn’t mix, and I elaborated by explaining that the water is denser than the oil and sinks to the bottom, because the molecules are so tightly packed together.  (I read recently that there are more molecules in a glass of water than there are known stars in the universe).  I went on to talk about how the water combines with the food coloring, but the oil does not.  I realized later that I could have gone into more detail about how water molecules are polar, with positive and negative poles like a battery, while the oil is nonpolar, with a shell of negative charges surrounding each molecule, and that polar and nonpolar molecules don’t mix well.

Since I was nervous about the carpet in the room I was working in, I added the oil to the bottles myself, filling each one about three-quarters full.  The kids then carried the bottles to the sink to fill them up the rest of the way with water.  I had them work at one big table for the rest of the project.  They each chose the color they wanted to dye the water, and dropped several drops of food coloring in.

Now for the big moment: I pulled out an Alka Selzer tablet and broke it up, dropping the pieces into my lava lamp.  The Alka-Selzer reacted with the water to create bubbles of carbon dioxide, which carried the green water droplets to the top of the bottle, where they would pop, and the water would sink back down.  The kids loved that part, and were eager to get their own Alka-Selzer tablets.  They spent the rest of the class happily plopping and fizzing.  I stretched a balloon over the top of my bottle, and showed them how it would fill up partially with air from the carbon dioxide.  They were eager to try that too.  Thankfully there were no brightly-colored oil spills!

The Carbon Dioxide in the Alka Seltzer will partially fill a balloon stretched over the mouth of the bottle

The carbon dioxide in the Alka Seltzer will partially fill a balloon stretched over the mouth of the bottle

At the end of class, I let them rinse the outside of their bottles off in the sink (they had all gotten a bit oily), and sent them home with their lava lamps and extra Alka Seltzer.  All-in-all, I had a great time, and they seemed to too.

Next week’s theme is Physics, and I’m planning to make Marshmallow Catapults.  I’m expecting a sugary battlefield.  Wish me luck!

Science in the Library: A STEM program for 5th and 6th Graders

A completed Spool Car

A completed Spool Car

Sorry for the embarrassingly long lapse in posts.  I’m still doing my regular weekly storytimes, but haven’t had time to write them up lately.  But recently I was asked to lead a series of STEM (Science Technology Engineering and Mathematics) workshops for grades 5 and 6 at the Burlingame Public Library, and yesterday was the first one.

I admit I was a tiny bit terrified of leading these workshops, since I usually work with much younger kids, and most of the actual instruction I’ve done has been in music and art. I was worried about finding science projects that would be challenging and interesting enough for tweens, yet not too complicated or expensive for an hour-long class.  But I had two wonderful aces in the hole: my coworker, Carbelle Imperial, who has been offering Make It classes at the Pacifica-Sharp Park Library for two years; and my son, who happened to be right in the target age group and the perfect guinea pig.  Carbelle gave me a list of web resources, and also pointed me towards some of the projects that worked the best for her.

For the first class, I chose the theme Science in Motion.  The library had required advanced registration, which was limited to 25 5th and 6th graders.  I ended up with 15 yesterday, which worked really well.

I started by introducing the topic of motion, and asking the kids what makes things move.  We talked for a few minutes about force and different types of energy, and then I pulled out a rubber band to demonstrate potential energy (the energy that is stored up when you stretch the rubber band out), and kinetic energy (the energy of motion created when you release it).  Then I introduced the spool car that we would be making.

The spool car was a project that Carbelle recommended.  I had played around with a couple of other rubber band car models that used CDs for wheels, but I could never find a reliable way to attach the CDs.  My kids gamely tried too, and for days our house looked like a miniature salvage yard.  Finally, Carbelle pointed me to the Instructables Spool Car from the Children’s Museum of Houston, which was vastly less complicated.  The only real challenge was tracking down large wooden spools (1.125″ x 2.75″), which I finally found at Michael’s (I snagged the last 5 packages in the store).

The model I ended up using in the class was actually based on Steve Spangler’s Wind Up Racer.  This one uses a pencil instead of a wooden skewer, and a toothpick instead of a paper clip to hold the rubber band in place.

To make the Spool Car, you first have to thread a rubber band through the hole of a wooden spool.  This is the hardest part of the whole project.  My son came up with the idea of creating a hook out of a pipe cleaner, attaching it to the rubber band, and then threading it through the spool.  Unfortunately, I forgot to bring pipe cleaners to the class, but we improvised with hooks made with paper clips.  It was still a struggle for the kids to thread the spools though, and I ended up having to help a number of them with this step.  It helps if you slide the toothpick through the rubber band at the end of the spool first, to anchor the rubber band and keep it from getting lost inside the hole.

Once you get the rubber band stretched all the way through the hole, thread it through a metal washer (I used 1/4″ x 7/16″ flat washers), and loop it around the pencil. Break the toothpick so that it no longer hangs over the edge of the spool, and tape it down with masking tape.

Side view of broken toothpick, stuck through the other end of the rubber band and held with masking tape

Side view of broken toothpick, stuck through the other end of the rubber band and held with masking tape

Now you have a spool car.  To make it go, wind the pencil clockwise several times, then set the whole thing down on a flat surface.  The rubber band unwinds, spinning the spool, and making it roll.

Side view of rubber band threaded through metal washer and looped around the pencil

Side view of rubber band threaded through metal washer and looped around the pencil

I had originally planned to have the kids race their spool cars, and then tweak them to see if they could improve their speed or reliability.  But the room we were working in had a carpeted floor, which made it harder to run the cars on.  Also, the kids were finishing their cars at different rates.  Instead, I challenged them to try out new designs, which they seemed to enjoy.  One girl attached a second pencil on the other side of the spool, and discovered that she could make the two pencils spin in different directions.  A boy attached two spools together to make a wider car.  They all seemed engaged in different ideas, some of them eagerly jumping up to share their discoveries, others working quietly on their own.

One thing I would do differently is to buy better quality rubber bands.  I had an assortment I purchased from Target, along with some I brought from home, but most of them broke after a few spins, which was frustrating for the kids.  Thicker rubber bands definitely work better, as well as rubber bands that are just long enough to go through the spool (some kids used longer rubber bands, but we ended having to tie knots in them to make the spool car work).  I think the race idea would have been a lot of fun too, although it might have made some of the shyer kids uncomfortable.  I had debated in the beginning about whether or not to have the kids work in pairs.  I didn’t end up doing that, but I noticed that a few of them ended up sharing ideas with other kids automatically, while others sat away from the larger groups.  I think I’ll probably just go with what they seem inclined to do naturally.

Although they all seem happily engaged in working with their spool cars, I had one more project I wanted to introduce.  I started by pulling out a balloon, and blowing it up with air.  I asked the kids whether the air inside the balloon was under high pressure or low pressure, and asked what would happen if I let it go.  We talked briefly about air always going from high to low pressure, and about the thrust that is created by air rushing out of a balloon.  Then I let the balloon fly wildly around the room, which they loved.  I asked if they could think of any way we could control where the balloon went, and several of them suggested changing the way I was holding it.  Then I said we were going to make a track for the balloon, and demonstrated the balloon rocket.

The balloon rocket is incredibly simple, but it was a huge hit.  All you do is inflate a balloon and tape a drinking straw to it (it’s easier if you cut off the “bendy” part of the straw).  I had one kid hold the end of a long piece of plastic cord, while I threaded the other end of the cord through the straw.  Then, when I stretched the cord to the other end of the room and let the balloon go, it went flying along the cord all the way across the room.

Completed balloon rocket, ready for launch!

Completed balloon rocket, ready for launch!

The one thing I forgot to bring for this was clothespins, which would have been helpful to keep the balloons closed until the kids were ready to “launch” them.  I did remember to bring two balloon pumps, which sped up the inflating process a lot.  I tied the cord to an easel on the far end of the room, and one by one the kids threaded their straws onto it and watched them fly across the room.  A few of them tried their own experiments.  One boy tied two balloons together, and then three.  To his surprise, they spun around the cord instead of going straight across, and didn’t make it all the way to the end.

At five minutes past the end of class, the kids were still happily playing with balloons, while their parents tried to hustle them out the door.   And while I was left with a lot of balloon and rubber band corpses to clean up, I was happy that they all seemed to have a good time.

Next week’s theme is chemistry.  So far, I am planning to make lava lamps, rubber balls, and demonstrate a “naked” egg, but I’d welcome any other suggestions!  Now that the first class is out of the way, I’m excited to see where the program goes.